Railway signaling apparatus



H. S. YOUNG RAILWAY SIGNALING APPARATUS May 4, 1943.

Filed Jan. *7, 1941 2 Sheets-Sheet 1 I I HIS ATTORNEY wag L L F May 4, 1943. H. s. YOUNG RAILWAY S IGNALING APPARATUS 2 Sheets-Sheet 2 INVENTOR paw . w m a m M A F 1 3 Eww HIS AZITORNEY Filed Jan. 7, 1941 Patented May 4, 1943 ilriilill) STAT-ES PATENT OFFICE 2,318,551 RAILWAY SI GNALING APPARATUS Henry 8. Young, -Wilkinsburg, l".a., assignor .to

The Union Switch"'& Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application January '7, 1941,. SerialgNo. 373,432

4 Claims.

My invention relates to railway signaling apparatus, and it has particular reference to the organization of such apparatus into railway signaling systems of the class wherein railway signals are controlled to govern the movement oftrafiic in both directions on a single track railroad. More particularly, my invention relates to the organization of apparatus into railway signal systems of the absolute permissive-block signal class.

Absolute permissive block (APB) signal systems are employed generally on single track railroads to govern trafiic between two successive passing sidings, and are arranged in such manner that when a train enters the stretch between the sidings, all of the opposing signals in-the stretch up to the next siding are set to stop,' while the signals in the rear of the train as it proceeds between the sidings are successively cleared to permit a second train to follow the first at the usual following distance. In such systems; it has been customary to utilize both track circuit and line wire control; and to provide the necessary directional control established when a train enters the stretch between sidings, it ha been customary to employ two line wires one for each divide novel and improved signal system in which a two wire line circuit is utilized together with the customary track circuit control to provide a novel and improved absolute permissive block signal system of signaling.

Another object is to'provide a signal system in which a two wire line circuit is utilized to control opposing signals to provide an absolute permlssive block signal system.

An additional object is to organize signalingapparatus into a novel and improved absolute permissive block signal system wherein a double wire, doublebreak control of two opposing signals is efiected utilizing only a two wire line circuit for controllingthe two opposing signals.

A further object is to organize signaling apparatus into a novel and improved absolute permissive block signal system wherein selective control of opposing signals is effected by supplying two distinctively characterized control currents to a, two wire line circuit.

Another object is to organize railway signal apparatus into a novel and improved absolute permissive blcck signal system in which thoriumher of line wires requiredis reduced toa minimum.

An additionalobject of myinvention ,is.to 'o.rganize railway signalizing apparatusinto' novel and improved absolute permissive block signal systems of signaling.

The above-mentioned and other important objects and characteristic features .of my invention which will .become readily apparent from the following. description, .are attainedlin. accordance with my invention by utilizing control means responsive only. to currenthavi'ngcert'ain characteristics .for cOntrollingone'. set for signals spaced alonga track andfgoverning .traflic'inf one direction, and utilizingother control; means responsive only. to current havingidistinctively different characteristics for controlling an opposingseto'i signals spaced along the. track and governing ltraflic inthe otherrdirectio'n. .The two control means for each pair of opposing signals are governed by a two wire line circuit supplied with each of the two distinctively characterized currents, and track circuit control ofisuchline circuit is provided to festablish directional control ofithe opposingsignalsinthe manner customary in absolute permissi'veblock signalisysterns. ,In addition, the'jtrack circuit control is arranged to break both Wires of. thetwo .wire line circuit so as to, obtain a double wire, .double. break controllforleach signal; and means. is provided for, preventing the opposing signal in the rear of a train .from clearing ,as the. train proceeds alon thestr'etch.

Otherimportantfeatures of my invention reside in. .thenparticular arrangement .of apparatus and organization of circuits .employed. rshau describe a preferred form of apparatus embody: inghmy invention, and shall. then point outthe el ea u es of. my invention in claims) In the. accompanying drawings, Figs. 1a and 1b are diagrammatic. views which when placed end to end with Fig. la on the left, representa preferred form of apparatuslgmbo dying my vention. Reierringto the drawing, the re f ere'n har r X de i na a tre c oran e track railroad cong st wi ucce ivep ssin smins L d;,: by sw t he w i h. designated by the reference character WWithflistinguishing isuffixes. Although only ,one lend Of Sidi ng L' is h n zth d awi s, it is .tofbe understood that both endsflf 1 iding areconne ted with-the e ch mi ar yitosiding; M.

Ihemils I and, la of track are dividedin-the ustomary manner by' insulated -jointslzfi' fia" a Pl a oflsuccessive djoining track sctidns will be referred to hereinafter as intermediate? sections.

Section I-I-.J and subsections D-Da, Dw-E, F-Fa and Fa--H are provided with track circuits each of which comprises a, track relay, designated by the reference character TR with a suitably distinguishing prefix, connected across the rails at one end of the section or subsection, as the case may be, and a suitable source of track circuit current connected across the other end. As shown in the drawing, alternating current sources of track circuit current are utilized, each comprising a track transformer, designated by the reference characters TT with a suitably distinguishing prefix, having a secondary winding 5 connected to the rails of the associated section or subsection, and having a primary winding 6 connected to a suitable source of alternating current, such as a generator not shown but having its two terminals represented in the drawing by the reference characters BX and CX.

The track relays TR, as shown, are alternating current relays having a local winding constantly supplied with alternating current from the source of alternating current, represented by terminals BX and GK, and having a track winding connected to the rails of the associated section or subsection. These relays are constructed in a manner well known so as to operate their associated armatures to a picked-up position when and only when both the local and track windings the current induced in secondary winding 5 of r the transformer and supplied to the rails of section E-F normally energizes a single element alternating current track relay 5ATR connected to the rails of the section intermediate the point at which secondary winding 5 of transformer 5TT is connected, and the adjacent end F of the section.

The reference characters S with suitably distinguishing prefixes, designate signals for governing traflic on track X. Two of such signals, one governing traific in one direction and the other governing traffic in the opposite direction, are located adjacent each pair of insulated joints defining track sections DE, E-F, etc. Signals bearing an odd-numbered prefix, such as 3, 5, etc, in their reference characters are arranged to govern eastbound traffic, that is, traific operating on track X from left to right as viewed in the drawings. The other signals having evennumbered prefixes before their reference characters are disposed to govern westbound traflic. These signals may be of any suitable form, such as position light, color light, searchlight, etc., but each is represented in the drawing as a color light signal having a green lamp G, a yellow lamp Y and a red lamp R, which lamps when illuminated indicate high-speed, reduced-speed and stop, respectively. The high-speed and reduced-speed indications will be referred to hereinafter as clear and caution indications, respectively.

Signals 3S and 8S governing the entrance of eastbound and westbound trains, respectively, into stretch X preferably are provided with suitable number plates, marker lights, or a combination of both to indicate that these signals are headblock signals. As shown, such signals are indicated to be headblock signals by providing each of these signals with two red lamps R, both energized in multiple when the signal is conditioned to display its stop aspect.

Signals 2S and 9S governing the entrance of westbound and eastbound trains, respectively, into the siding sections, I shall refer to hereinafter as entering signals. The other signals disposed intermediate headblock signals (is and 8S, and entering signals 2S and 9S, I shall refer to hereinafter as intermediate signals.

Associated with ach signal S there is a polarized signal control relay, designated by the reference character HDR with a prefix corresponding to the prefix of the associated signal. The signal control relays HDR associated with the set of westbound signals are arranged to respond only to current having certain characteristics, while those associated with the opposing set of eastbound signals are arranged to respond only to current having distinctively different characteristics. For the purposes of this description, I shall assume that the two distinctively characterized currents are supplied respectively from a source of alternating current and a source of unidirectional current. I shall further assume that the HDR control relays associated with the westbound signals are alternating current relays responsive only to alternating current and that the HDR control relays associated with the eastbound signals are unidirectional relays and respond only to unidirectional current.

Associated with each signal control relay HDR.

- there is a slow acting repeater relay, designated 'cuit which extends from one terminal B of a suitable source of direct current, such as a battery not shown, through front contact l2 of relay 3I-IDR and the Winding of relay 3HDPR to the other terminal N of the source of current. Each repeater relay associated with an alternating current polarized signal control relay, such as relay 4HDR is energized over an obvious circuit including either a normal or a reverse polar contact of its associated polarized signal control relay. Relay 4I-lDPR is energized, for example, over a circuit extending from terminal B through contact l3 closed in the normal or reverse position of relay lI-IDR, and the winding of relay 4HDPR to terminal N.

Each signal control relay HDR cooperates with its associated repeater relay HDPR in controlling the asociated signal S in such manner'that when the signal control relay is energized in its normal direction to operate its polar contact member l6 to its normal or left-hand position, as viewed inthe drawings, the .associatc'dxsignal is controlled toz'display Eitsproceed indication; when the signal control-relay is energized with current of reverse polarity and operates its .polar contact member l6 to the reverse position, the associated signal is controlled to display its caution indication; and :when the signal control relay and its repeater relay'are deenergized, the :associated signal iscontrolled to display its .stop indication. For example, when polarized signal .control relay 3HDR is energized in ,its normal direction, relayL3'HDPRis energized and'lamp G of signal 38 is illuminated by current supplied over a circuit extending from terminal BX through front contact [4 of relay SHDPR, front contact l5 and polar contact I6 closed in the normal or left-hand position. of relay 3HDR, and the filament :of lamp G :of signal 3S to terminal CX. When relay 3I-IDR is energized in its reverse direction, polar :contact member I6 is operated to its right-hand position to open the previously traced 'circuit of lamp G, and a reverse polar contact ofxrelay 3I-1'DR is closed to complete an obvious circuit for lamp Y of signal 3S. When relay '3HDR is deenergized, its front contact I2 is opened to in turn deenergize relay 3HDPR so that back contact Moi relay '3HDPR is closed to complete anobvious energizing circuit for lamps R of signal 35.

Associatedwith each intermediate signal 48, 5S, 'ESand 1S there is a directional control stick relay, designated by thereference character SR with a distinguishing prefix corresponding to the prefix of the associated signal. Each stick relay normally is deenergized, andbecomes picked up when the section governed by the associated signal-becomes occupied provided that the opposite intermediate signal is set to stop. That is to "say, when section EF becomes occupied by aneastbound train so that relay 5TB. drops, relay 58R associated with signal 5S picks up provided that relay dHDPR is released to control the opposite intermediate signalASto stop, A'pickup circuit for relay 58R, completed under the assumed conditions,-may be traced from terminal B through back contact 80 of relay 4HDPR, back contact 8i of relay 5TB, front contact 82 of relay SI-HDPR and the winding of relay ESR to terminal N. Each stick relay when picked-up completes aholding circuit which is effective to hold such relay-energized until the train vacates the section next in advance of the section governed by the associated signal.

Overlap control means is provided for each intermediate section adjacent a siding section. An overlap control relay 2DPR is provided for section D-E adjacent siding L; an overlap control relay IODPR is provided for the intermediate section immediately to the east of siding section H-J; and overlap controlfor section F-H adjacent siding M, isprovided by utilizing'polar contactmembers of signal control relay BI-IDR, as will be made clearpresently.

Each of the switches W operates a'first contact l8 and a second contact 19, which contactsare closed only when the respective switchis in its normal position, that is, theposition for directing trafic over stretch X only and not to or from'its passing siding. In order to simplify the drawings, I have omitted showing-the mechanisms which cause operation of switches W to take place, it being :understood that such switches maybemanually and/or power operated by suitable.mechanisms-.-well known in theart.

""Each two opposing signals governing tra'fiic over a section .arercon'trolled by :a two wire line circuit which extends from one end of the section .to the othenand by two sources ofcurrent, one connected rtonone endof the line circuit and the other connected .to the .otherend. .Thetwo sources of .current connected :to' each line circuit include a source of alternating current, repre sented in the drawingszas a transformer designated by .thereference character LT with a suitablyidistinguishing prefix, having a primary winding 20 connected to the source of alternating current and .a secondary winding i2l connected to one end of theassociated line circuit; and a source of unidirectional current, which latter source may be a battery but which is represented in the drawings as a full-wave rectifier, designated by the reference character LB with a distinguishing prefix, having its input terminals connected .throughatransformer to a source of alternatingzcurrent and having its output terminals connected to the other end of theassociated linecircuit. Each source is: connected to its associated line circuit at the end of the-section opposite that at which 'islocated the signal controlled by the polarized relayresponsive only -'to that form of current. That-is to say, the signal control relays associated with theeastbound signals, such as signal control relays 3HDR, 5HDR, etc., .as stated previously are responsive only-to direct current. In accordance withthe usual custom,'relay 3HDR, for-example, is located adjacent the associated'signal 3S positionedadjacent end D of section D-E, hence rectifier 313R is connected to the line circuit of section D-'E at the opposite .endE of the section. Transformer 4LT islof course, connected to the line circuit of section D-E at the left-hand end B, for controlling relay lHDRpositioned adjacent and:.controlling1signal 4S located at end E of the section.

' In order to simplify thedrawings, I have represented contacts of relays at times disposed remotefrom the relays operating such contacts, but in each case each of such contacts has been represented in the normal condition which it assumes and has been identified not only by a reference character individual to such contact, but also by placing immediately above such contact'the referencecharacter of the relay causing that contact to operate. For example, the reference character 2DPR. has been placed immediately above contact 23 to indicate that this contact is operated by relay ZDPR, and'the contact is represented in a closed front position to indicate that-such relay is normally energized.

As represented in the drawings, the apparatus embodying my invention is ,in'its normal condition, that is, each section D,IE, E--F, F-H, HJ is unoccupied; each switch W isin its normal position; each signal S is indicating proceed; each intermediate section (not shown) between section H-Jand the next siding to the east of siding M is unoccupied; and each section (not shown) between section'D-E' and the next siding west of siding L is unoccupied. With these various sections mentioned unoccupied, 'thetrack relays TR shown in the drawings are energized, and overlap relay ZDPR is energized.

Each signal control relay I-IDR also is energized by current of what I shall term normal polarity, and consequently operates its'polar'contact members to theirleft-hand or'normal-positions so as :tozcon-trol the 'associatedsignaP to 'its clearindication. For example, signal control relays 3I-IDR and 4HDR, controlling opposing signals 38 and 48, respectively, are energized over a two wire line circuit which may be traced from thelefthand terminal,"as-;viewed in the drawing, of secondary .windingi2lof transformer 4LT, through resistorl24, :front contact 23 of overlap relay 2DPR, front contact 25. of relay 3TB, of subsection DDa, line wire 26, front contact 2! of. relay 4TB of subsection Dar-E, front contact 28 of signal control repeater relay SHDPR, associated with signal 5S, reactor 29, rectifier 3LR, front contact 30 of relay SHDPR, front contact 3| of relay 4TR, line wire 32, front contact 33 of relay 3TB, and front contact 34 of relay ZDPR to the other or right-hand terminal of winding 2| of transformer 4LT. The control winding of relay 4HDR is connected through back, contact 35 of stick relay 58R and front contact 21 of relay 4'IR to line wire 26 of the above traced circuit and is connected through a resistor 35 and front contact 3| of relay 4TB to lower line wire 32. The polarity of current supplied from transformer 4LT to relay 4I-IDR is controlled by overlap relay ZDPR, which relay is effective when energized to close its front contacts 23 and 34 to condition, when relays 3TR and 4TB, are also energized, the

line circuit to supply relay 4HDR with alternatingcurrent having one relative instantaneous polarity which I shall term normal polarity, but which relay ZDPR when released closes its back contacts 23 and 34 to therebyreverse the polarity of current supplied to relay II-EUR, as is readily apparent from an inspection of the drawings.

Relay 3HDR is connected, as is readily appar-' its front contacts 28-and 30 and conditions the line circuit to supply current of one relative polarity, which I shall term normal polarity, to relay 3HDR, and which relay 5HDPR when released closes its back contacts 28 and 30 to reverse the polarity of current supplied to relayv 3HDR, provided that relay 58R is picked up to close its front contact 35. In the event that relay SSR is released when relay EHDPR. is released, then the circuit of relay 3HDR is opened, as can be seenfrom an inspection of the drawings.

The line circuit of section E-F, controlling the energization of relays SHDR and BHDR, is substantially similar to the line circuit just traced for section DE, with the exception that a back contact 31 of stick relay 48R is interposed in the connection of relay 5HDR to line wire 26 of the line circuit of section E-F, and front contact 3'! of relay 48R is interposed in the connection of back contact 40 of relay 4HDPR to line wire 26.

The line circuit of section F-H, controlling the energization of relays 'lI-IDR and BHDR, also is substantially similar to the line circuit previously traced for section DE, with the exception that relay "IHDR is connected through back contact 60 of relay SSH and front contact 5| of relay 1TR. to the upper line wire 26 of that line circuit; the other control relay BHDR is connected to the line wires directly without the interposition of a contact of a stick relay SR; and polar contact members 53 and 56 of relay SHDR are interposed in the line circuit to pole change the current supplied'from rectifier 'lLR to relay 'IHDR, as is readily apparent from an inspection of the drawing. These pole changing polar con tact members of relay 9HDR function to provide overlap control of signal'lS in a manner to be explained presently.

- The line circuit controlling the energization of relays QHDR and IllI-IDR, is also similar to the line circuit of section DE, except that contacts l8 and IQ of switch W2, and contacts l8 and I9" of switch W3, are interposed in the line circuit of section HJ, as is readily apparent from an inspection of the drawings. Furthermore, both relays SHDRand IDHDR. are connected to the line circuit without the interposition of contacts of the previously mentioned stick relays SR.

With the signal control relays HDR all energized by current of normal polarity, all repeater relays HDPR are energized; all signals S are controlled to display their repective clear indication and all stick relays SR are released.

- I shall now assume that an eastbound train enters the first intermediate section (not shown) east of the first siding west of the section withv which siding L is connected. Relay ZHIDR is thereby caused to reverse its polar contact members in substantially the same manner as relay lDHDR is caused to shift its polar contact members when the eastbound train enters section DE, as will be explained presently, and signal 28 accordingly is caused to display its caution indication over an obvious circuit passing from terminal BX through front contact l4 of relay ZHDPR, polar contact member [6 of relay 2HDR in its reverse position and the filament of lamp Y of signal 28 to terminal CX. Overlap relay 2DPR, 1 which is energized over normal contact ll of relay ZHDR, also is caused to release, with the:

result that its front contacts 23 and 34 open and its back contacts 23 and 34 close to reverse the polarity of energization of relay 4HDR in a manner readily apparent from an inspection of the drawing, and signal 48 thereupon is controlledto its caution indication over an obvious circuitsimilar to that just traced for lamp Y of signal: 28. This condition of the apparatus is main-' tained until the train enters thesection immediately to the west of section DE, whereupon relay 2TB associated with such section releases to cause the release of relay ZHDR. Relay 2HDPR. also releases when the polar contact members of relay 2HDR assume their deenergized or mid positions and signal 2S accordingly is controlled to display its stop indication when back contact l4 of relay ZHDPR closes to complete an obvious circuit for lamp R of that signal.

When the train enters the first intermediate section, DE, between passing sidings L and M, all signals governing traflic in the opposite, or

westbound, direction between the sidings are set I dication when back contact l4 of repeater relay 3HDPR closes due to the interruption of the energizing circuit of relay 3HDPR when relay 3HDR. releases, while signal 4S is controlled to its stop condition over a circuit completed over back contact 14' of relay- AHDPR, which latter relay releases in response to the release" of relay 4HDR.

The releasing of relay AHDPR and consequent opening of its contacts 40 and 45 disconnects transformer 6LT from the line circuit of section E'F, as is readily apparent from an inspection of thedrawings, and relay BHDR controlled by alternating current supplied to the line circuit of section E F accordingly releases to cause the release in turn of relay BHDPR. when back contact M of relay BHDPR'closes, signal 63 is controlled to display its stop indication, and when front contacts 59- and 59 of relay GHDRP' open, transformer 8LT is disconnected from the line circuit of section F-H, with the result that relay BHDR is caused to release.

Relay BHDPR. thereupon releases to close its back contact I4 and control signal 88 to its stop condition, and back contacts 64 and 13 of relay 8HDPR close to" re verse the polarity of alternating current supplied from transformer IULT' to relay IOHDR, as is readily apparent from an inspection of the drawing'. Relay IOHDR accordingly reverses its polar contact members, thereby causing overlap relay IUDPR to release and signal HIS to assume its caution indication, in a manner similar to that mentioned hereinbefore in connection with the reversal of thepolar contact members of relay ZHDR, when the train enters the first intermediate section east of'the first siding west ofsiding-L;

When the train enters subsection Da/E, relay 4TB. releases to open its front contacts 21 and 3-! interposed in the line circuit of sectionD E;

but the releasing of relay 4TB. at this time' does not affect the-condition of the apparatus previously described. If the train is'relatively short, it will vacate the section to the west of section DE prior to entering section and when the section west of section DE becomes vacat ed, relay ZTR. picks up to close its front contacts interposed in the-line circuit of such'section to condition relay ZHDR tobeenergized in its normal direction in a manner similar to that herein; after to beexplained in detail in connection with relay liiHDRwhensection H-J becomes vacated. The energizationof relay ZHDR at normal polarity causes relaysZDPR and ZI-IDPR tobe energized, the latterrelay in turn completing the previously traced energizing circuit of lamp G of signal ZSto cause that'signal to display its clear indication; The eastboundappara'tus as; sociated with the sectionimmediately totheWeSt of section D-E is not atthis time restored 'to its normal condition, however; since with the train in subsection DDa, relay 3TB; is released and holds open its front contacts interposed in the line circuit of the section west of section D-E, and back contacts of relay 3HDPR, interposed in the same circuit, are also closed. When relay 3TB, picks up upon the train vacating subsection D-Da, its front contacts interposed in the line circuit of the section to the west of section D'E, and contacts 25' and 33 inteiposed inithe line circuit of section DE, become closed, butthe line circuit of section D-E is held open at front contacts 21 and 3| of relay :tTR.

When the train enters section E-F relay TH is first shuntedand releases to open its front contacts M and 45 interposed in the line circuit of section Relay EHDR thereupon is deenergized and releases to open its front contact l2 and thereby open the energizing circuit of its repeater relay B-I-IDPR, but prior to the release of relay SHDPR, that is; during the slow release interval of such relay, stick relay ESR becomes energized over a. circuit extending from terminal i B through back contact of relay AHDPR, back contact 8| of relay STR, front contact 82 of rela'y 5HDPR. and the winding of relay 58R to terminal N. Relay 'JSR accordingly picks up to close its front stick contact 83, thereby preparing a stick circuit which becomes completed when back contact 82' of relay 5I-IDPR closes at circuit-of section D-E, which alternate path will be'referred to presently. v v.

Signal 58 of course assumes its'sto'p' condition when relays EHDPR and EHDR'release, thereby indicating that section EF is'occupied.

If, now, the train vacateslsubsection"DaQE,

'relay 4TH, picks upand closes its fronta -contacts 21 and 3| with the result that current of reverse polarity is supplied to relay 3HDR over a circuit extending from the upper or positive terminal of rectifier 3LR through reactor 29, back contact 2 8 of relay BHDPR; front contact 3| of relay 4TB, line'wire 32, front contact'33' of "reIayBTR th e winding of relay 3HDR, frontjcontact 25 0f relay 3TH, line wire 25, front contact 21 0f reIa'y lIR, front contact 35 of relay 58R, and back contact 30 of relay 5I-IDPR to the lower or negative terminal of rectifier 3LR. Relay 3I-lDRivfaccordingly reverses its'polar contact members and. closes its front contact [2 to'reenergiz'e relay 3HDPR, whereupon lamp Y of signal3S'becomes energized over a circuit extending from terminal BX through front'contact Mof relay3HZlI)P1 front contact E5 and polar contact l 6 of relay 3HDR- in its reverse position, and the filament of 'lamp Y of signal 3S to terminal CX. t

r The energization of relay 4TB, do'esnot'at this t me cause relay 4I-IDR to become reenergized, sincewith relay 55R energized; back contact 35 of relay 56R is opened to disconnect relay 4I-IDR from the line circuit of section D-.-E. Relay 4HDR accordingly remains released andsignal 48 continues to display its stop aspect.' It follows, therefore, that the opposing signal governmg traflic in the-section next inv the rear of an occupied section is prevented from clearing and is held at its stop condition, whereas the signal governing following movemen'tsiin'- the section next in the rear of an occupied'section is controlled to its caution indication to permit followmgfmoves at the customary followingldistance.

As the train approaches right-handend F of section E--F,l relay. 5ATR, is shunted and. re-,

leases to open its front contact 42 interposedin the line" circuit of section E- -F,-' and when the train enters section F-H, relayJlTR- associated with subsection F-Fa is first shunted andreleases to open its front contacts 5'! and 58 interposed in the line circuit of section Relay THDR. thereupon becomes deenergized and releases 'to open its front contact l2-to open the energizing circuit of relay IHDPR, but prior to the release of the latter relay, which of course setssignal 18 to stop, relay "ISR. becomes energized over a circuit extending from terminal B through back contact'85 of relaytiHDP lt;v back contactllt of relay lTR, front contact 81 of relay 'IHDPR, and the winding of'rel'ay 'ISR to terminal N. Relay TSR accordingly picks up to close its stick front contact 88 to prepare its stick circuit, which circuit becomes completed when back contact 81 of relay 'lI-IDPR closes at the end of a slow release interval of that relay. Relay TSR also closes its front contact 41 to prepare an alternate path in the line circuit of section E-F, this alternate path being effective when relays TR and 5ATR pick up as the rear of the train vacates section E-F, to condition current of reverse polarity to be supplied over back contacts 43 and 44 of relay 'lI-lDPR to relay 5HDR, which latter relay accordingly becomes energized to swing its polar contact members to their re verse positions, and to close its front contact l2 and thereby reenergize relay SHDPR. When relay 5I-IDPR picks up at the end of its slow pick-up period, signal 58 is controlled to its caution indication over an obvious circuit including front contact I4 of relay 5HDPR and front contact l5 and polar contact l6 of relay 5HDR in its reverse position; front contacts 28 and 30 of relay SHDPR interposed in the. previously traced normal line circuit of section D-E become closed; and the previously traced stick circuit of relay 5SR is interrupted at back contact 82 of relay 5I-IDPR so that relay 58R releases to close its back contact and reconnect relay 4HDR to the line circuit of section DE. Relays 3HDR and ll-IDR thereupon become energized by current of normal 8TR becomes shunted and releases to open its front contacts 52 and 51 interposed in the line circuit of the associated section, and front contacts 65 and I2 interposed in the line circuit of section HJ, thereby deenergizing relay IUHDR, which latter relay releases to cause the release in turn of overlap relay IDDPR and repeater relay IOHDPR. When relay IOI-IDPR releases, signal 108 is controlled to its stop indication.

Relay ITR picks up whenv the train vacates subsection F -Fa. Then, when the train enters siding section HJ, relay 9TR releases to open its front contacts 66 and H and thereby open the circuit of relay 9HDR, which relay accordingly releases toflc'ausein turn the release-of relay SHDPR, thereby controlling signal 98 to its .stop indication. Relay 9HDPR also closes its back contacts 54 and 55 interposedin the line circuit of sectionFH, to condition current of reverse polarity to be, supplied to relay IHDR when relay 8TB picks. jup t0, close its front contacts 52 an 51 whenthetrain'yacates section FH. 7 1 I The energizationofrelay THDR by current of reverse polarity/causes its'polarcontact members to be operated to their reverse positions, and causes itsjront contact IZ to.be closed to reenergize repeater relay 'IHDPR. .When relay ll-IDPR picksup, signal 18 is controlled to its caution indication} front contacts .43 and 44 of relay 1HDBR int1erposed in the line circuit of section E-,F,become closed; back contact .Bl-of relay 'IHDPR opens toopen the previously mentioned stick circuit of relay 'ISR whereupon the latter releases to close its back contact 41 and reconnect relay GHIDR to the line circuit of section E'-F; relays 5HDRand BHDR become energized by current of normal polarity; relay 6HDPR is reen'ergizedandplcked up, and signals 58 and 68 are bothlcontrdlled to theirnormal clear condition.

Relay 8HDR also becomes energized when relay .8TR picks up, the current supplied to relay 8HDR however being of normal polarity so that when repeater relay 8HDPR becomes reenergized, signal BS is controlled to its clear condition.

When the train vacates section HJ and relay 9TB picks up, relay IBHDR becomes energized by current of normal polarity and operates its polar contact members to their normal position to cause relays IODPR and IOHDPR in turn to pick up. When relay IOHDPR picks up, signal MS is cleared, but signal 98 remains in its stop condition since the circuit of relay SHDR is open at front contacts 61 and 1B of relay IB'IR, associated with the section immediately to the east of section HJ. When relay IU'IR picks up, current of reverse polarity first is supplied to relay 9HDR over back contacts 68 and 69 of relay HHDPR (the signal control repeater relay, not shown, of signal HS) so that relay SHDR operates its polar contact members to their reverse positions, and closes its front contact I2 to reenergize repeater relay 9HDPR. When relay SHDPR picks up to close its front contact l4, signal BS is controlledto its caution condition; and when front contacts 54 and 55 of relay 9HDPR close, current of reverse polarity is supplied to relay 'IHDR over contact members 53 and 56 of relay SHDR in their reverse positions. Relay 'IHDR accordingly retains its polar contact members in their reverse positions to retain signal 18 at its caution indication. When, however, relay I IHDPR picks up to close its front contacts 68 and 69, current of normal polarity is supplied to relay 9HDR so that signal 93 is controlled to its clear condition, and polar contact members 53 and 56 are operated to their normal positions so that current of normal polarity is supplied to relay 'IHDR and as a result signal is also is controlled to its clear condition.

It is believed that the operation of the apparatus embodying my invention for a westbound train will be readily apparent from an inspection of the drawing and from the foregoing description of the operation of the apparatus for an eastbound train, and further detailed explanation is deemed unnecessary except to point out that when the westbound train enters the first intermediate section West of the first siding east of section HJ, relay SHDR is caused to operate its polar contact members to their reverse positions, thereby controlling signal 98 to its caution indication, due to the polarity of energization of relay 9HDR being reversed in a manner substantially similar to that pointed out whereby the polarity of energization of relay I OHDR is reversed when an eastbound train enters section DE. The reversal of the polar contact members 53 and 56 of relay 9I-IDR of course causes the polarity of energization of relay THDR to be reversed, thereby causing signal IS to be controlled to its caution indication and providing overlap control for signal is.

In addition, it should be pointed out that when a westbound train operates between sidings M and L, the stick relays SR associated with the westbound signals 6 and 4 ar caused to be energized to hold the opposing signals 7S and 58 at stop when the train occupies the section next in advance of the section governed by such opposing signals.

From the foregoing description, it is readily apparent that I have provided a novel and improved arrangement whereby an absolute permissive block signal system of signaling is provided and in which only two line wires are required for controlling each pair of opposingsignals; In addition, it is evident that the track circuit control ofthe two line'wires is effective to open both wires, thereby providing maximum assurance against crosses and/or grounds and providing a double wire, double break system of control.

Although I have herein shown and described only one form of railway signaling apparatus embodying my invention, it is understood that various changes and modifications may be made therein Within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a railway signal system for a stretch of railway track having an insulated section provided with a pair of conductors extending from one end to the other of said section, a source of direct current connected to one end and a source of alternating current connected to the other end of said conductors respectively, two stick relays, means responsive to traflic on said stretch,

means controlled by said trafiic responsive means for energizing one or the other of said stick relays according as traffic operates over said stretch in one direction or the other respectively, two control relays one responsive only to direct current and the other responsive only to alternating current, means including a back contact of said one stick relay for connecting said direct current control relay to said conductors at said other end of said section in multiple with said alternating current source, means including a back contact of said other stick relay for connecting said alternating current control relay to said conductors at said one end of said section in multiple with said direct current source, and means controlled by said two control relays for governing trafiic operating in either direction through said section.

2. In a railway ignal system for a stretch of railway track divided into a plurality of successive adjoining insulated sections including a first, a second and a third section adapted to be traversed in the order named by a train operating in one direction on said stretch, a track circuit for each of said sections, a pair of conductors extending from one end to the other of said second section, a source of direct current connected to one end and a source of alternating current connected to the other end of said conductors respectively, two stick relays one for said third section and the other for said first section, a pick-up and a stick circuit for said one stick relay controlled by the track circuits of said second and said third sections whereby to energize said one stick relay only when a train operates over said stretch in said one direction, a pick-up and a stick circuit for said other stick relay controlled by the track circuits of said second and said first sections whereby to energize said other stick relay only when a train operates over said stretch in the opposite direction, two control relays one responsive only to direct current and the other responsive only to alternating current, means including a back contact of said one stick relay for connecting said one control relay to said other end of said conductors in multiple with said alternating current source, means including a back contact of said other stick relay for connecting said other control relay to said one end of said conductors in multiple with: said: direct current source; means? controlled by said one control relay forrgoverning trafiic operating. in" said one direction: inasaid. section, and means. controlled by'sai'd' other control relay for governing traific operating in said other direction. in said section,

3: In a railway signal system for a stretch of railway." track divided into' a plurality of: successive adjoining; insulated section's. including a first, a second: and -a third section: adapted tob'e traversed -in the'order. namedi by afltra'in' operating in one direction on said stretch, a track circuit for each of said sections, a pair of conductors extending from one end to the other of said second section, a source of direct current connected to one end and a source of alternating current connected to the other end of said conductors respectively, means governed by the track circuit of said first section for controlling the polarity of current supplied from said direct current source to said conductors, means governed by the track circuit of said third section for controlling the polarity of current supplied from said alternating current source to said conductors, two stick relays one for said third section and the other for said first section, a pick-up and a stick circuit for said one stick relay controlled by the track circuits of said second and said third sections whereby to energize said one stick relay only when a train operates over said stretch in said one direction, a pick-up and a stick circuit for said other stick relay controlled by the track circuits of said second and said first sections whereby to energize said other stick relay only when a train operates over said stretch in the opposite direction, two control relays one responsive only to direct current and the other responsive only to alternating current, means including a back contact of said one stick relay for connecting said one control relay to said other end of said conductors in multiple with said alternating current source, means including a back contact of said other stick relay for connecting said other control relay to said one end of said conductors in multiple with said direct current source, means controlled by said one-control relay for governing trafiic operating in said one direction in said section, and means controlled by said other control relay for governing trafiic operating in said other direction in said section.

4. A railway signal system for a stretch of railway track divided into a plurality of successive adjoining track sections including a first and a second and a third section traversed in the order named by a train operating in a given direction over said stretch, a track circuit including a track relay for each of said sections, a pair of conductors extending from one end to the other of said second section, a first source of current, a second source of current having characteristics distinctively different from said first source, means controlled by the track relay of said first section for normally connecting said first source to one end of said conductors, means controlled by the track relay of said third section for normally connecting said second source to the other end of said conductors, two directional stick relays, circuit means controlled by the track relays of said second and third sections for energizing one of said stick relays only when a train operates over said stretch in said given direction, circuit means controlled by the track relays of said second and first sections for energizing the ductors in an alternate path, means including a back point of a contact of said other stick relay for normally connecting said other control relay to said one end of said conductors in multiple with said first source and including a front point of said contact for at times connecting said first source to said conductors in an alternate path, and signal means controlled by said two control relays for governing trafiic operating in either 10 direction in said second section.

HENRY S. YOUNG. 

